Growing plants indoors requires the grower to control and manage all facets of the plant growing environment. Historically, a substantial problem in growing plants indoors is keeping a constant human vigilance in maintaining ideal water saturation. The grower must also manage the light exposure, nutrients, and a litany of other complicated balances to enhance plant growth, but the most fundamental element is and always has been water.
The present invention relates to the electronic controller solutions available for growing plants indoors, specifically hydroponic or ebb and flow systems. The ebb and flow watering system as referenced herein, necessarily includes a control bucket, that is in fluid communication with the plant containers at the same elevation, such that the water level in the control bucket, is the same as the water level in the plant containers. Float switches that indicate water level and trigger pump action are also standard, and generally one is located at the bottom of the control bucket to signal empty, and one at the top to signal full. Water pumps that are either on or off move fluid from a reservoir into the control bucket, that then gravity fills the plant containers. An electromechanical timer initiates fill and drain cycles based on user set time periods. Varying methods implemented in the prior art enable these components to work in cooperation, allowing for the timely watering of plants.
For the beginning hydroponic or ebb/flow grower, the management of watering is a first priority, as the absence of soil reduces the margin of error for maintaining adequate moisture but not too much. Ebb and flow gardening requires a controlled regimen cycle of flooding the media which holds the moisture until the next cycle, and then quickly and completely draining the water before unhealthy conditions develop at the plant root system. If the cycles of watering are too far apart, the plants suffer drought conditions, and if the cycles are too close together, over watering can stunt growth or cause disease. Leaving the roots under water or “Root Wet” conditions can also lead to hypoxia in the root cluster, which could lead to fatal plant disease. In short, water management, when growing with an ebb/flow system, is critical for success.
Multi-cycle timers like the described electromechanical short interval timer as shown and described in Flaig U.S. Pat. No. 4,490,051 is a common solution to the watering problem, as the timer turns on and off pumps that facilitate the watering of the plants. The motorized electromechanical timer usually has a dial with a periphery of receiving apertures, and the dial rotates once during a 24 hour period. Depending on user placement of small “tabs” within the periphery apertures of the timer's dial, the timer's rotation toggles (activates and deactivates) an electrical switch within the timer turning electrical components on and off. The tabs may be moved around the dial to accurately set the desired component or watering schedule.
Coupling the electromechanical timer and water pumps with mechanical float switches in a control bucket is a common configuration for ebb and flow gardening. The water gravity feeds from the control bucket to the plant containers along flood lines. The control bucket is at the same elevation and in fluid communication with the plant containers, so the level of water in the control bucket is approximately the same as the level of water in the plant containers. The timer triggers a fill pump to come on, and the fill pump runs until the upper float switch located at the top of the control bucket shuts the pump off when the “Full” level is reached in the control bucket. After the desired time passes per the timer, the timer triggers the drain pump to come on to remove the water from the control bucket and plant containers, pumping the water from the control bucket (and the plant containers) back into the reservoir to be recycled or reused for the next watering cycle. When the lower float switch located at the bottom of the control bucket indicates empty, the mechanical float switch shuts off the drain pump. The above described system provides the basic watering control for the standard ebb and flow systems.
The shortcoming of the timer and float switch combination arises from the hydraulic flow delay between fluid movement between the control bucket and the plant containers or vice versa, as water migration does not occur instantaneously. There may be several flood lines in fluid communication with one control bucket, and each flood line has a plurality of plant containers. Just because the control bucket is “Full” does not mean that all of the plant containers down each flood line are “Full”. Gravity fills the plant containers from the control bucket, so the filling of containers is slowed by the limitations of fluid flow at the fittings, grow media, and hose lines. In the common ebb and flow configuration, the control bucket may be at the correct water level when the fill pump shuts off, but as the plant containers finish gravity filling, the level in the control bucket recedes or goes down, leaving the plant containers short on water. Similarly during the drain cycle, the lower float switch may indicate drained, and shut off the drain pump, but water from the flood lines and plant containers are still draining back which results in water standing at undesirable levels in the control bucket and plant containers.
To help illustrate by prior art example, when the electromechanical timer signals ‘fill’ the fill pump is powered on with the upper float switch connected in series so that when the upper float switch is down the circuit between the electromechanical timer relay and the fill pump is closed. When the upper float switch floats to the full position, the circuit between the electromechanical timer relay is broken, the fill pump is shut off. The problem lies in the water being pumped into the control bucket is entering at a faster rate than the water flowing out of the control bucket down the flood lines and to the plant containers. After the upper float switch indicates ‘full’ and the fill pump is shut off by the circuit being broke, water continues to recede in the control bucket due to the delay of water flowing down the flood lines, resulting in inadequate levels of water at the plant containers. Due to the hydraulic delay described, when the upper float switch finally drops to a level that signals the fill pump to come back on, the electromechanical timer has timed past the ‘fill’ cycle, so the fill pump stays off, and the plant containers are not watered adequately.
Other problems with using the prior art float switches that signal ‘open’ or ‘closed’ only, is waves or disturbances within the control bucket. If a float switch is set to signal with more accuracy, then it becomes more susceptible to waves in the control bucket which create false ‘full’ signals which shut the fill pump off, and when the float drops a little as caused by a disturbance, the fill pump is turned back on. This on and off pump cycling is a problem not resolved in the prior art.
The drain cycle is performed much the same way, having the drain pump shut off when the lower float switch drops indicating that the control bucket is adequately drained, opening the circuit thereby shutting off the drain pump. The hydraulic delay of water flowing back through the flood line from the plant containers raises the lower float switch that closes the circuit to the drain pump, causing the drain pump to come back on, only if the electromechanical timer is still in the ‘drain’ cycle. If the hydraulic delay is such that the ‘drain’ cycle has ended, the water flowing back is not removed by the drain pump, and an undesirable level of water is left in the plant containers causing a root wet condition. This root wet condition can be detrimental to plant health.
If a less accurate float switch is used that requires considerable change in level before signaling, the fill or drain pump is shut off initially when the desired level is reached, and not turned back on until the level changes considerably, and usually not until after the electromechanical timer has already run through it's ‘fill’ or ‘drain’ cycle. Conversely, the more accurate of float switches used, as in the float switch indicates with less change in level, the more susceptible the system is to pulsing the pumps on and off due to waves in the control bucket or under conditions when the hydraulic delays closes match the pump flow. Over cycling the pumps on and off excessively is undesirable, as it causes premature failure of the pump, makes for unnecessary noise, increases power consumption, and decreases the life of the electrical components of the ebb and flow system.
Other problems not addressed in the prior art relate to shutting off the pumps if there is a problem with the system. For example, water leaking from the flood line would cause the upper float to drop, turning on the fill pump, pumping water until the reservoir is empty, or until the timer ends its fill cycle. A reservoir may hold 55 gallons, which if pumped out onto the floor may cause considerable damage. Similarly, a ‘run dry’ prior art problem occurs when the reservoir gets too low to fill the flood lines, control bucket, and plant containers during the fill cycle. The fill pump is turned on but the control bucket never reaches the desired level, and the upper float switch remains down, keeping the fill pump powered. When the reservoir runs out of water, the fill pump continues to run dry until failure.
Visual indication of fill or drain states have been implemented in prior systems, and are historically accomplished by the use of LEDs that become lit when the corresponding pump is powered. The user can then look and see which pump is running to understand whether the system is filling or draining, but no further indication information is available. Visual indication advances have been implemented in the prior art that requires additional float switches which then turn on and off LEDs depending on water level in the control bucket effectively tied to a particular float switch in the control bucket. However, the addition of float switches increase expense, while decreasing reliability.